#include <stdio.h>
long long n, res, MOD=1000000007;
long long pow(int a, long long b) {
if(a==0) return 0;
else if(a==1 || b==0) return 1;
else {
long long P = pow(a, b/2)%MOD;
if(b%2) return (P%MOD)*(P%MOD)*(a%MOD);
else return (P%MOD)*(P%MOD);
}
}
int main() {
scanf("%lld", &n);
if(n==1) res=4;
else if(n==2) res=12;
else {
if(n%2) {
res=pow(3, n)+1;
}
else {
res=pow(3, n)+3;
}
}
printf("%lld", res%MOD);
}
To embed this project on your website, copy the following code and paste it into your website's HTML: